The field of the invention relates to idle speed control systems for motor vehicles having fuel vapor recovery systems coupled between the fuel system and engine air/fuel intake.
It is known to maintain idle speed of a motor vehicle at a desired idle speed by feedback control of a bypass throttling device. During idle speed control operation, purging of the fuel vapor recovery system through the engine air/fuel intake is typically disabled.
The inventor herein has recognized a need and provided a system to purge the fuel vapor recovery system during engine idle. With such a proposed system, approximately seventy-five percent (75%) of inducted air during idle may be contributed from the fuel vapor recovery system. If purging subsequently ceases during engine idle, insufficient air may be inducted to maintain engine idle during the transient response time of the feedback loop. Engine stumble or stall may therefore result.